In previous articles, we have talked about what an algebraic expression is and how to get the numerical value of algebraic expressions. Today, we will cover equivalent expressions.

Equivalent expressions are two or more algebraic expressions that represent the same value. They may have a different structure, but their numerical value will be the same.

For example, in the following equation both sides represent the same quantity:

9X=3X+6X 9X=3X+6X

Below is another example with 2 variables. By simplifying the expressions on both sides of the equation, we can work out that on both we have 2X3Y+5 2X-3Y+5 and therefore the expressions are equivalent.

2X3Y+5=X+X2Y+105Y 2X-3Y+5=X+X-2Y+10-5-Y

Practice Equivalent Expressions

Examples with solutions for Equivalent Expressions

Exercise #1

18x7+4x98x=? 18x-7+4x-9-8x=\text{?}

Video Solution

Step-by-Step Solution

To solve the exercise, we will reorder the numbers using the substitution property.

18x8x+4x79= 18x-8x+4x-7-9=

To continue, let's remember an important rule:

1. It is impossible to add or subtract numbers with variables.

That is, we cannot subtract 7 from 8X, for example...

We solve according to the order of arithmetic operations, from left to right:

18x8x=10x 18x-8x=10x 10x+4x=14x 10x+4x=14x 79=16 -7-9=-16 Remember, these two numbers cannot be added or subtracted, so the result is:

14x16 14x-16

Answer

14x16 14x-16

Exercise #2

7.34a+2.3+8a=? 7.3\cdot4a+2.3+8a=\text{?}

Video Solution

Step-by-Step Solution

It is important to remember that when we have numbers and variables, it is impossible to add or subtract them from each other.

We group the elements:

 

7.3×4a+2.3+8a= 7.3×4a + 2.3 + 8a =

29.2a + 2.3 + 8a = 

37.2a+2.3 37.2a + 2.3

 

And in this exercise, this is the solution!

You can continue looking for the value of a.

But in this case, there is no need.

Answer

37.2a+2.3 37.2a+2.3

Exercise #3

9m3m2×3m6= \frac{9m}{3m^2}\times\frac{3m}{6}=

Video Solution

Step-by-Step Solution

According to the laws of multiplication, we must first simplify everything into one exercise:

9m×3m3m2×6= \frac{9m\times3m}{3m^2\times6}=

We will simplify and get:

9m2m2×6= \frac{9m^2}{m^2\times6}=

We will simplify and get:

96= \frac{9}{6}=

We will factor the expression into a multiplication:

3×33×2= \frac{3\times3}{3\times2}=

We will simplify and get:

32=1.5 \frac{3}{2}=1.5

Answer

0.5m 0.5m

Exercise #4

3x+4x+7+2=? 3x+4x+7+2=\text{?}

Video Solution

Answer

7x+9 7x+9

Exercise #5

3z+19z4z=? 3z+19z-4z=\text{?}

Video Solution

Answer

18z 18z

Exercise #6

Are the expressions the same or not?

20x 20x

2×10x 2\times10x

Video Solution

Answer

Yes

Exercise #7

Are the expressions the same or not?

3+3+3+3 3+3+3+3

3×4 3\times4

Video Solution

Answer

Yes

Exercise #8

Are the expressions the same or not?

18x 18x

2+9x 2+9x

Video Solution

Answer

No

Exercise #9

x+x= x+x=

Video Solution

Answer

2x 2x

Exercise #10

5+89+5x4x= 5+8-9+5x-4x=

Video Solution

Answer

4+X

Exercise #11

5+0+8x5= 5+0+8x-5=

Video Solution

Answer

8X 8X

Exercise #12

11+5x2x+8= 11+5x-2x+8=

Video Solution

Answer

19+3X

Exercise #13

7a+8b+4a+9b=? 7a+8b+4a+9b=\text{?}

Video Solution

Answer

11a+17b 11a+17b

Exercise #14

13a+14b+17c4a2b4b=? 13a+14b+17c-4a-2b-4b=\text{?}

Video Solution

Answer

9a+8b+17c 9a+8b+17c

Exercise #15

a+b+bc+9a+10b+3c=? a+b+bc+9a+10b+3c=\text{?}

Video Solution

Answer

10a+11b+(b+3)c 10a+11b+(b+3)c

Topics learned in later sections

  1. Variables in Algebraic Expressions
  2. Multiplication of Algebraic Expressions
  3. Simplifying Expressions (Collecting Like Terms)
  4. The Numerical Value in Algebraic Expressions
  5. Transposition of terms and domain of equations of one unknown.
  6. Domain of a Function